Nitrous acid primary aliphatic amines

In the aliphatic series, primary amines are deaminated by nitrous acid, secondary aliphatic amines are A-nitrosated, while tertiary aliphatic amines form salts in the acidic medium followed by secondary reactions such as dealkylation [1, 21a, b]. 

If an aromatic and an aliphatic amino group are both contained in the molecule, as in 4-aminobenzylamine, the aromatic amino group can be replaced without affecting the primary aliphatic group for this purpose an aqueous solution of sodium nitrite is dropped into a solution of the amine in hypophosphorous acid, primary aliphatic amines being indifferent to nitrous acid below pH 3.547... 

They are readily hydrolysed by boiling dilute hydrochloric acid and the original amine can be recovered by neutralisation with alkali and steam distillation. Primary aliphatic amines liberate nitrogen with nitrous acid whilst tertiary amines are unaffected. 

Primary aromatic amines differ from primary aliphatic amines in their reaction with nitrous acid. Whereas the latter yield the corresponding alcohols (RNHj — ROH) without formation of intermediate products see Section 111,123, test (i), primary aromatic amines 3neld diazonium salts. Thus aniline gives phcnyldiazonium chloride (sometimes termed benzene-diazonium chloride) CjHbNj- +C1 the exact mode of formation is not known, but a possible route is through the phenjdnitrosoammonium ion tlius ... 

Diazobenzene Sulphate.—Whereas nitrous acid immediately decomposes the primary aliphatic amines wdth et olution of nitiogen,... 

Demjanov rearrangement org chem A structural rearrangement that accompanies treatment of certain primary aliphatic amines with nitrous acid the amine will undergo a ring contraction or expansion. dem ya-nof re-3 ran -m3nt) denaturant chem An inert, bad-tasting, or poisonous chemical substance added to a product such as ethyl alcohol to make it unfit for human consumption. de na-chs rsnt ... 

The action of nitrous acid on a primary, aliphatic amine is still a complex process, inasmuch as it is necessary to postulate certain steps that are imperfectly understood, but it can nevertheless be considered that the process leads ultimately to a carbonium ion.26,27 The carbonium ion thus formed is termed hot, that is to say, it is non-solvated and chemically activated the nature of the products resulting from its decay is essentially determined by the conformation of the initial state the electronic factors in effect at the time of the transition state exert little influence.27... 

Scheme 1. Action of nitrous acid on a primary, aliphatic amine...

The best known example of the treatment of a primary aliphatic amine with nitrous acid involves the reaction of esters of glycine hydrochloride with sodium nitrite to form esters of diazoacetic acid. This reaction is carried out at low temperatures and under such reaction conditions that any IV-nitroso primary amine which might have been formed is immediately converted to the diazoacetate [15, 16]. Treatment of 1-methyl-2,2,2-trifluoroethylamine hydrochloride, another primary amine, with sodium nitrite in an aqueous system also evidently leads to the corresponding diazoalkane [17]. 

It was suggested8 in 1932 that carbonium ions are intermediates in the conversion of a primary aliphatic amine into nitrogen-free products by the action of nitrous acid. In the weakly acidic solutions normally used for deamination of aliphatic amines, the rate-determining... 

Our understanding of the deamination of primary aliphatic amines by the action of nitrous acid has gained much from studies of alicyclic compounds, including Shoppee s extensive work in the steroid field. 

When the electron-deficient atom is the nitrogen atom of nitrous acid or nitrosyl chloride, the products will depend on whether the amine is a primary or secondary amine. Primary aliphatic amines give rise to dia-zonium salts (RNj X) which readily decompose, sometimes with rearrangement. Aromatic diazonium salts (ArNj X ) are very important in aromatic transformations, and are discussed later. Secondary amines, on the other hand, give rise to nitrosamines... 

Primary aliphatic amines also react with nitrous acid to yield diazonium salts but since aliphatic diazonium salts are quite unstable and break down to yield a complicated mixture of organic products (see Problem 23.11, below), this reaction is of little synthetic value. The fact that nitrogen is evolved quantitatively is of some... 

Primary aliphatic amines react with nitrous acid to form diazonium salts (Sec. 23.10). 

Problem 36.15 The reaction of primary aliphatic amines with nitrous acid gives a quantitative yield of nitrogen gas, and is the basis of the Van Slyke determination of amino nitrogen. What volume of nitrogen gas at S.T.P. would be liberated from 0.001 mole of (a) leucine, (b) lysine, (c) proline — ... 

Treatment of a primary aliphatic amine with nitrous acid or its equivalent produces a diazonium Ion which results in the formation of a variety of products through solvent displacement, elimination and solvolysis with 1,2-shift and concurrent elimination of nitrogen. The stereochemistry of the deamination-substitution reaction of various secondary amines was investigated as early as 1950, when an Swl-type displacement was suggested. Thus, the process can hardly be utilized for the preparation of alcohols except in cases where additional factors controlling the reaction course exist. Deamination-substitution of a-amino acids can be utilized for the preparation of chiral alcohols. 

Undoubtedly the same reaction occurs with aliphatic primary amines and nitrous acid. With aryl amines, however, the diazonium ion is stabilized by the resonance forms,... 

Van Slyke determination. Treatment of primary aliphatic amines and a-amino acids with nitrous acid and volumetric determination of evolved nitrogen. 

Aliphatic Diazo Compounds.—It has been stated that primary aliphatic amines do not yield diazonium compounds when treated with nitrous acid. It is of interest to note, however, in connection with the aromatic diazo compounds, that certain derivatives of the ahphatic amines yield compounds when treated with nitrous acid which resemble somewhat in their reactions the diazonium compounds. When the ethyl ester of amino-acetic acid is treated with nitrous acid a yellow oil is obtained, which explodes when heated. The reaction takes place according to the equation,—... 

A Reactions of Primary Aliphatic Amines with Nitrous Acid... 

Primary aliphatic amines react with nitrous acid through a reaction called diawtization to yield highly unstable aliphatic diazonium salts. Even at low temperatures, aliphatic diazonium salts decompose spontaneously by losing nitrogen to form carbocations. The carbocations go on to produce mixtures of alkenes, alcohols, and alkyl halides by removal of a proton, reaction with H2O, and reaction with X ... 

Primary aliphatic amines (RNH2) react with nitrous acid in the same way that primary arylamines (ArNH2) do, to form diazonium ions. But alkyldiazonium ions RN2 are much less stable than aryldiazonium ions ArN2 and readily lose nitrogen even at 0°C. Explain the difference. 

Treatment of a primary aliphatic amine with nitrous acid results in the loss of nitrogen, N2, and the formation of substitution, elimination, and rearrangement products as illustrated by the treatment of butylamine with nitrous acid. 

Because treatment of a primary aliphatic amine with HNO2 gives a mixture of products, it is generally not a useful reaction. An exception is the Tiffeneau-Demjanov reaction, in which a cychc 8-aminoalcohol is treated with nitrous acid to give a ring-expanded ketone, with evolution of nitrogen. 

The mechanism is analogous to diazonium ion formation using nitrous acid and aliphatic primary amines. 

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